Building regs re toilet provision was updated in 2024 -
2024 edition This approved document supports Part T of Schedule 1 to the Building Regulations 2010. This approved document takes effect on 1 October 2024 for use in England. Full details of the transitional arrangements can be found in Circular 02/2024 published on gov.uk.
Toilet accommodation: Approved Document T
I'm not an expert on UK Building Regs, to say the least, though I seem to have the URL of Doc T on speed-dial😁and I know the regs have limited application, i.e. mostly new builds.
However I think they are useful in that the 2024 update strongly reinforced the primacy of single-sex toilet provision in public buildings - yes you can have unisex facilities as well as, but, as I understand it, only in the case of a lack of space can you have them instead of single sex facilities.
'Document T' is an assertion that the standard, and the 'direction of travel' in the future, is single-sex toilets, and it's valuable for that reason alone.
There are other regulations that cover single sex facilities - workplace regs, health and safety, equality legislation - so it's always worth looking at the full range of relevant regs rather than - as has happened a lot in the wake of the SC ruling - just the Equality Act to make a case.